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The Airy beam has attracted great attention since it was proposed in 2007 due to its novel properties, such as non-diffraction, self-healing, and self-acceleration. However, the spin angular momentum (SAM), which is an intrinsic nature of light, has rarely been studied by the Airy beam. Here, we propose a kind of binary circular Airy beam (BCAB) with space-variant polarizations and vortex phases and study the SAM evolution of the BCAB during propagation. We find the effects of appearance and annihilation of SAM during the propagation of BCAB, and the SAM can be further manipulated by adjusting the initial phase and polarization distribution of BCAB. Moreover, the optical tube, optical needle, and optical cage carrying different SAMs are achieved in propagation, which can be applied in various regions, such as optical trapping and manipulation. The BCAB significantly enriches the family of structured light and provides a flexible control scheme of SAM, which can further promote the application of SAM in many fields. [ABSTRACT FROM AUTHOR]

High-order vortex beams carrying orbital angular momentum in the visible wavelength range are of tremendous interest for a diversity of applications, including super-resolution imaging, microfabrication, and underwater communications. Such beams can be generated directly from compact solid-state lasers; however, they generally have low topological charge number. In this work, we demonstrate the generation of high-order Laguerre–Gaussian (LG) modes from a simple Pr:YLF laser cavity and demonstrate its application in the measurement of angular velocity. We utilize enhanced intracavity spherical aberration to generate LG0,±m modes with m selectable up to 34, directly from a Pr:YLF laser operating at 640 nm. We utilize this laser beam in an off-axis illumination geometry in conjunction with the rotational Doppler effect, to measure the angular velocity of a spinning object. The demonstration highlights a potential application for these types of vortex laser. [ABSTRACT FROM AUTHOR]

A total of 207 householders from 13 natural villages in the Naban River Watershed National Nature Reserve were chosen for a systematic survey on the farming and livestock husbandry, aimed to evaluate the effects of planting rubber and crops on the keeping number of livestock and poultry in the study area. The livestock and poultry bred in the Reserve were mainly buffalo, Yunnan Yellow cattle, small-eared pig, Chahua chicken, and a few Banna game fowls. Exotic breeds were very limited. From 1991 to 2008 , the planting area of rubber increased year by year, giving negative effects on the corn, rice, and cash crop production as well as the keeping number of livestock and poultry. Planting rubber had significant negative effects on the keeping number of buffalo and small-eared pig. The families planting rubber kept significantly less buffalo and small-eared pig, as compared to those not planting rubber. The planting areas of corn, rice, and cash crops had positive effects on the keeping number of buffalo, Yunnan Yellow cattle, and small-eared pig, and the total planting area of the crops had active effects on the keeping number of buffalo and Chahua chicken. The development of rubber production led to an obvious change in land use pattern, which in turn had significant effects on the keeping number of livestock and poultry. With the increasing rubber planting area year by year, the local livestock husbandry would be restrained. [ABSTRACT FROM AUTHOR]

The controlled visible spatial modes and vortex beams with tunable properties are highly sought after in cutting-edge applications, such as optical communication. In this study, by utilizing a hybrid pumping scheme, we demonstrate an ultra-compact, 607 nm orbital Poincaré laser based on a diode-pumped Pr:YLF laser. The system can generate various structured modes, including Laguerre-Gaussian (LG), Hermite-Gaussian (HG), and Hermite-Laguerre-Gaussian (HLG), all of which are mapped onto a first-order orbital Poincaré sphere. A numerical analysis of the coherent superposition of HG modes with varying phases is in complete agreement with the experimental results. The handedness of the generated vortex beam can be selectively controlled by precisely adjusting the angle of output coupler. In comparison to other schemes, the hybrid pumping scheme offers advantages of high precision and excellent tunability, enabling the emitting of high-order HG modes, LG modes, along with a wide range of spatial modes on the orbital Poincaré sphere. Our scheme can also be extended to different gain media, which could lead to the creation of structured beams with richer wavelength, offering a promising platform for innovative studies on multidimensional light-field control.

Colorectal cancer (CRC) is one of the most common cancers worldwide. Early detection and removal of colorectal polyps during colonoscopy are crucial for preventing such cancers. With the development of artificial intelligence (AI) technology, it has become possible to detect and localize colorectal polyps in real time during colonoscopy using computer-aided diagnosis (CAD). This provides a reliable endoscopist reference and leads to more accurate diagnosis and treatment. This paper reviews AI-based algorithms for real-time detection of colorectal polyps, with a particular focus on the development of deep learning algorithms aimed at optimizing both efficiency and correctness. Furthermore, the challenges and prospects of AI-based colorectal polyp detection are discussed., Competing Interests: None., (AJCR Copyright © 2024.)

Based on the longitudinal manipulation of polarization, a special vector optical beam (VOB) with customized polarization variation in propagation direction can be generated, whose properties and applications remain to be studied. Here, the self-healing propagation behaviors of the longitudinally varying VOB after an opaque object are investigated, and the localized polarization responses on the object distance are revealed. On this basis, characteristic parameters are defined to measure the distance of object, achieving a minimum relative error of 0.63% in a longitudinal range of 300 mm. Besides, the correlations and uncoupling methods of object distance and size are discussed. Our studies open new ways to use the structural properties of VOB and may be instructive for laser measurement.

Curved filament with large bent angle and controllable propagation behavior has always been great expectation and challenge due to its novelty and complexity. The unique properties of curved filaments make it possible to achieve many applications in micro-fabrication, spectroscopy and meteorology. Here we realize experimentally and theoretically control on helical filaments induced by twisted beams in CS 2 . The results show that helical filaments exhibit a robust pattern and high rotation rate. Specific intensity pattern of the twisted beam confines the filaments in fixed relative position and the azimuthal energy flux drives the rotating of the filamentation pattern. In addition, we demonstrated that the global orbital angular momentum (OAM) of twisted beams is still conservative to be zero, but local OAMs exhibit distinct variation during nonlinear propagation. Our idea has its significance which realizes the construction of helical filaments with flexibility and controllability and then facilitates to push the development of related researches.

A total of 207 householders from 13 natural villages in the Naban River Watershed National Nature Reserve were chosen for a systematic survey on the farming and livestock husbandry, aimed to evaluate the effects of planting rubber and crops on the keeping number of livestock and poultry in the study area. The livestock and poultry bred in the Reserve were mainly buffalo, Yunnan Yellow cattle, small-eared pig, Chahua chicken, and a few Banna game fowls. Exotic breeds were very limited. From 1991 to 2008, the planting area of rubber increased year by year, giving negative effects on the corn, rice, and cash crop production as well as the keeping number of livestock and poultry. Planting rubber had significant negative effects on the keeping number of buffalo and small-eared pig. The families planting rubber kept significantly less buffalo and small-eared pig, as compared to those not planting rubber. The planting areas of corn, rice, and cash crops had positive effects on the keeping number of buffalo, Yunnan Yellow cattle, and small-eared pig, and the total planting area of the crops had active effects on the keeping number of buffalo and Chahua chicken. The development of rubber production led to an obvious change in land use pattern, which in turn had significant effects on the keeping number of livestock and poultry. With the increasing rubber planting area year by year, the local livestock husbandry would be restrained.